We had a German Shepherd who had a seizure disorder with grand mal seizures and Riley, my SM dog, had one siezure early in December. Her neurologist gave me some diazepam (valium) to keep with me in case she had another, but so far that was the only one. Like Nicki and Karlin said, sometimes they may just have that one. Hopefully that will be the case with Roscoe.
My German Shepherd was a different story. She had a seizure disorder for the last 5 years of her life (she died when she was almost 13) but was well controlled on medication for her last two years and had no seizures. She was on phenobarbitol and potassium bromide. Her vet gave me the phenobarb, but the potassium bromide had to be specially formulated at a pharmcay and then they mailed it to me. I also had valium on hand to give her if she had more than one in a row. One Christmas, she had seven of them right in a row - no time to recover in between. She went to the emergency hospital and was put on a valium drip and was kept for several days while they tried to control her.
What Roscoe went through sounds pretty typical of my german shepherd's experience. She would always take a while to recover. Sometimes she would stand with her nose in a corner until she got her balance back, sometimes she would circle me, but always touching me - seemed like she always wanted contact with one of us while she was recovering. Recoveries took quite a while - sometimes hours, but then she was back to her normal self running, jumping, eating well, happy.
Like Karlin said, your vet will probably do blood tests - there are a number of medical disorders that can cause seizures (diabetes, I think). We also had an MRI of our shepherd's brain to see if it was a tumor after all medical causes had been ruled out (negative luckily). They finally just called it late-onset epilepsy.
Try not to worry too much and let us know what the vet says.